Conventional hand-held garden tools, for example pruning snips, typically comprise an upper and a lower cutting blade, each having an elongated handle extending therefrom and configured to pivot about a single axis. For a constant force applied to the handles, the force generated at the cutting blades is essentially constant throughout the cutting stroke.
Shearing heavy growths, for example shrubbery and tree branches, however, often requires considerably greater force than that generated by single axis hand-held tools. The need for greater cutting force is especially pronounced where the operator's hand is small or otherwise not capable of delivering significant force to the handles.
In general, the use of compound leverage action mechanisms to increase the ratio of force applied at the handles to force delivered at the blades is well known. Compound leverage mechanisms have been employed, for example, in hook-and-blade-type pruning apparatus, in anvil-type tools, and in shears. Examples of such pruning apparatus are described in U.S. Pats. Nos. 4,420,883 and 4,442,603 issued to E. Wallace, et al. on Dec. 20, 1983 and Apr. 17, 1984, respectively. Examples of compound action shears are described in U.S. Pats. Nos. 492,198, issued to C. Hamann on Feb. 21, 1983, U.S. Pat. No. 2,384,822, issued Sept. 18, 1945 to S. Drmic, U.S. Pat. No. 2,528,816, issued to H. Boyer on Nov. 7, 1950, and U.S. Pat. No. 3,650,028, issued to G. LaPointe on Mar. 21, 1972. Use of compound action leverage mechanisms in lopping shears is also known, for example as described in U.S. Pat. No. 3,372,478, issued to E. Wallace, et al. on Mar. 12, 1968 and pending U.S. patent application Ser. No. 07/012,890, filed Feb. 10, 1987 by Wallace, et al.
However, known compound action leverage tools tend to be disadvantageous in a number of respects. Spring mechanisms, typically employed to urge the handles into the open position, are often disposed between the handles or otherwise external to the device. Consequently, the spring mechanism tends to become entangled in tall grass or nearby branches, thereby impeding the cutting process. Further, the stopping mechanism, typically employed to reduce shock to the cutting blades during closure thereof, tends to be relatively complex, thereby adding to the fabrication costs of the hardware.